lists.openwall.net | lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC | |
Open Source and information security mailing list archives
| ||
|
Date: Tue, 08 Sep 2015 23:34:02 +0200 From: Vitaly Kuznetsov <vkuznets@...hat.com> To: Greg Kroah-Hartman <gregkh@...uxfoundation.org> Cc: Stephen Hemminger <stephen@...workplumber.org>, "K. Y. Srinivasan" <kys@...rosoft.com>, Haiyang Zhang <haiyangz@...rosoft.com>, x86@...nel.org, linux-kernel@...r.kernel.org, Ingo Molnar <mingo@...nel.org> Subject: Re: [PATCH] hyperv: fix build if KEXEC not enabled Ingo Molnar <mingo@...nel.org> writes: > * Vitaly Kuznetsov <vkuznets@...hat.com> wrote: > >> Ingo Molnar <mingo@...nel.org> writes: >> >> > * Stephen Hemminger <stephen@...workplumber.org> wrote: >> > >> >> Fixes regression 4.3 mergw window in my config >> >> where hyperv is enable but CONFIG_KEXEC not enabled. >> >> >> >> arch/x86/kernel/cpu/mshyperv.c:112: undefined reference to `native_machine_crash_shutdown' >> >> >> >> Introduced by: >> >> commit b4370df2b1f5158de028e167974263c5757b34a6 >> >> Author: Vitaly Kuznetsov <vkuznets@...hat.com> >> >> Date: Sat Aug 1 16:08:09 2015 -0700 >> >> >> >> Drivers: hv: vmbus: add special crash handler >> >> >> >> >> >> Signed-off-by: Stephen Hemminger <stephen@...workplumber.org> >> >> >> >> >> >> --- a/arch/x86/kernel/cpu/mshyperv.c 2015-09-07 10:11:24.994885115 -0700 >> >> +++ b/arch/x86/kernel/cpu/mshyperv.c 2015-09-07 10:14:20.995698615 -0700 >> >> @@ -109,7 +109,9 @@ static void hv_machine_crash_shutdown(st >> >> { >> >> if (hv_crash_handler) >> >> hv_crash_handler(regs); >> >> +#ifdef CONFIG_KEXEC >> >> native_machine_crash_shutdown(regs); >> >> +#endif >> > >> > I think there's another related bug as well: >> > >> > machine_ops.crash_shutdown = hv_machine_crash_shutdown; >> > >> > that should be #ifdef CONFIG_KEXEC as well AFAICS. >> > >> >> Why? [...] > > Because you are bloating the kernel. > > That's because machine_ops.crash_shutdown() does nothing outside of kexec and > that's the existing pattern in the native and KVM code. (Xen does it > inconsistently as well.) > > So you bloat the kernel at minimum, and also confuse the reader what it's all > about. > >> [...] crash_shutdown is defined in machine_ops unconditionally, I don't see why >> we _need_ #ifdef here (and btw Greg insisted on removing them). > > So arguably the kexec interface should be cleaned up as well, into something like: > > kexec_crash_handler_set(hv_machine_crash_shutdown); > > ... which would compile to no code at all in the !KEXEC case, and then we could > also make ::crash_shutdown #ifdef KEXEC. > > At least one #ifdef is unavoidable unless we make KCONFIG an always-enabled > facility - or merge it more intelligently with the regular > reboot/shutdown code. Greg, I don't personally have a strong opinion here but I'm leaning towards Ingo's suggestion. That would mean I have to break your 'no #ifdefs in C files' rule (ok, I can move everything to mshyperv.h to respect it but that would feel like a fraud). Please let me know if you prefer such fix to the previously posted one (https://lkml.org/lkml/2015/8/11/417). Thanks, > > I.e. I don't think there should be kexec specific 'handlers' per se - there should > be reboot/shutdown handlers that will also serve kexec just fine. > > But until that's fixed we've got to make the best of the existing kexec design. > > Thanks, > > Ingo -- Vitaly -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
Powered by blists - more mailing lists